The Justice Department announced Tuesday its largest-ever financial seizure — more than $3.5 billion — and the arrests of a New York couple accused of conspiring to launder billions of dollars in cryptocurrency stolen from the 2016 hack of a virtual currency exchange.

Federal law enforcement officials said they recovered roughly $3.6 billon in cryptocurrency linked to the hack of Bitfinex, a virtual currency exchange whose systems were breached nearly six years ago.

Ilya “Dutch” Lichtenstein, a citizen of Russia and the United States, and his wife, Heather Morgan, were arrested in Manhattan on Tuesday morning, accused of relying on various sophisticated techniques to launder the stolen money and conceal the transactions. They face federal charges of conspiracy to commit money laundering and conspiracy to defraud the United States. It was unclear if they had lawyers or people who could speak on their behalf.

They were in custody pending an appearance in Manhattan's federal court later Tuesday.

The stolen cryptocurrency, valued at $71 million at the time of the theft, is now valued at $4.5 billion, officials said.

The couple were not charged in the Bitfinex hack, which resulted in more than 2,000 unauthorized transactions. But prosecutors said they received stolen bitcoin into a digital wallet they controlled and used money laundering techniques such as setting up accounts with fictitious identities to hide their activities and the movement of the money.

Millions of dollars of the transactions were cashed out through bitcoin ATMs and used to purchase gold and non-fungible tokens as well as more mundane items like Walmart gift cards for personal expenses, prosecutors said.

Justice Department officials say that though the proliferation of cryptocurrency and virtual currency exchanges represent innovation, the trend has also been accompanied by money laundering, ransomware and other crimes

“Today’s arrests, and the Department’s largest financial seizure ever, show that cryptocurrency is not a safe haven for criminals,” Deputy Attorney General Lisa Monaco said in a statement. “In a futile effort to maintain digital anonymity, the defendants laundered stolen funds through a labyrinth of cryptocurrency transactions. Thanks to the meticulous work of law enforcement, the department once again showed how it can and will follow the money, no matter the form it takes.”